Lunarians are Moon niggers. They sent those moon crickets to Earth. Joy Boy is a West African and Caribbean myth.
You know how in Naruto, Kaguya basically came down to Earth, ate some fruit, and created chakra? What if The One Piece is something like that?
So the Lunarians come down to Earth, meet the great kingdom which is where the D. Initial comes from, and the great treasure is basically some type of moon produce that basically ends up being the devil fruits we know about?
And then Joy Boy takes to the sea with his awesome powers, and after 100 years, he’s beaten, and the guys who beat him take this gift from the moon people as a trophy of conquest, or at least the fruit(s), along with Joy Boy’s hat, and that trophy of conquest is the treasure of Mary Geoise, which is the source of the transformation for Imu and the Gorosei. With the less powerful ones turning into the devil fruits we know and love thanks to either Imu’s garden, or the treasure of Joy Boy having fruit fall into the ocean and going to parts unknown.
And the “funny story” is how Joy Boy manages to keep the gift from the moon people out of the hands of his enemies, staying fresh for the time that the chosen one comes to finish the fight Joy Boy started.
In short, my sure to be wrong prediction is that the One Piece is this tree/orchard/farm that has a bunch of produce that puts the Devil fruits to shame, and Joy Boy managed to not just keep it out of the hands of the World Government, but leave it prime and ready for Luffy and the rest of the Straw Hats to use to their advantage in the final showdown against Imu and company in the World Government.